improve eww

modules/home/wayland/apps/eww/bar/scripts/brightness

@@ -1,29 +1,34 @@
 #!/usr/bin/env bash
+# Backlight brightness (first device under /sys/class/backlight).  Refreshes
+# on backlight udev events, which also fire for the hardware keys.
+#
+#   brightness              status loop (deflisten)
+#   brightness set PERCENT
 
-BACKLIGHT="/sys/class/backlight"
-DEV=$(ls "$BACKLIGHT" 2>/dev/null | head -n1)
+dev=""
+for d in /sys/class/backlight/*; do
+  [[ -e $d ]] && { dev=${d##*/}; break; }
+done
 
-gen_output() {
-  if [ -z "$DEV" ]; then
-    echo '{"percent":0,"available":false}'
-    return
-  fi
-  max=$(cat "$BACKLIGHT/$DEV/max_brightness")
-  cur=$(cat "$BACKLIGHT/$DEV/actual_brightness" 2>/dev/null || cat "$BACKLIGHT/$DEV/brightness")
-  percent=$(awk -v c="$cur" -v m="$max" 'BEGIN{print int(c/m*100+0.5)}')
-  printf '{"percent":%d,"available":true}\n' "$percent"
+state() {
+  [[ -n $dev ]] || { printf '{"percent":0,"available":false}'; return; }
+  local max cur
+  max=$(<"/sys/class/backlight/$dev/max_brightness")
+  cur=$(cat "/sys/class/backlight/$dev/actual_brightness" 2>/dev/null \
+    || cat "/sys/class/backlight/$dev/brightness")
+  printf '{"percent":%d,"available":true}' "$(((cur * 100 + max / 2) / max))"
 }
 
-case "$1" in
-  set)
-    [ -z "$DEV" ] && exit 0
-    brightnessctl -d "$DEV" set "${2}%" -q 2>/dev/null
-    ;;
+refresh() { emit "$(state)"; }
+_bl_events() { exec udevadm monitor --udev --subsystem-match=backlight; }
+
+case ${1:-} in
+  set) [[ -n $dev ]] && brightnessctl -q -d "$dev" set "${2%.*}%" ;;
   *)
-    gen_output
-    [ -z "$DEV" ] && exit 0
-    udevadm monitor --udev --subsystem-match=backlight 2>/dev/null | while read -r _; do
-      gen_output
-    done
+    refresh
+    [[ -n $dev ]] || exit 0
+    mux_init
+    mux_add _bl_events
+    mux_loop refresh
     ;;
 esac